Optical fiber, dispersion compensator, and optical transmission system

Abstract

The present invention relates to a compact dispersion compensator and the like. The dispersion compensator comprises a housing and an optical fiber coil. The optical fiber coil has a coiled part constituted by a dispersion-compensating optical fiber wound like a coil while being in a bundle state with its winding distortion substantially eliminated. The housing is filled with a resin surrounding the coiled part of the optical fiber coil, whereas the coiled part is held by the resin. By this structure, the dispersion compensator can realize a further compactness.

What is claimed is: 
     
       1. A dispersion compensator, comprising:
 an optical component having an accumulated chromatic dispersion of −1200 ps/nm or more but less than −600 ps/nm at a wavelength of 1.55 μm; and 
 a housing having a volume of 500 cm 3  or less for accommodating said optical component, 
 wherein said optical component includes an optical fiber coil which is obtained by winding an optical fiber in a coil form such that an insertion loss of said entire dispersion compensator becomes 5.9 dB or less while being accommodated in said housing. 
 
     
     
       2. A dispersion compensator according to  claim 1 , wherein the volume V (cm 3 ) of said housing and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     V ≦−0.31× AD +120.
 
 
     
     
       3. A dispersion compensator according to  claim 1 , wherein the insertion loss IL (dB) at the wavelength of 1.55 μm and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     IL≦− 0.0033× AD +1.9.
 
 
     
     
       4. A dispersion compensator according to  claim 1 , wherein an optical fiber constituting said optical fiber coil, comprises:
 a center core part extending along a predetermined axis and having a predetermined maximum refractive index; 
 a first cladding part, provided on an outer periphery of said center core part, having a refractive index lower than that of said center core part; 
 a second cladding part, provided on an outer periphery of said first cladding part, having a refractive index higher than that of said first cladding part; and 
 a third cladding part, provided on an outer periphery of said second cladding part, having a refractive index lower than that of said second cladding part. 
 
     
     
       5. A dispersion compensator according to  claim 4 , further having, as a characteristic at the wavelength of 1.55 μm, a bending loss of 0.1 dB/km or less in a state wound at a diameter of 60 mm. 
     
     
       6. A dispersion compensator according to  claim 4 , wherein said second cladding part has a relative refractive index difference of 0.2% to 0.9% with reference to the refractive index of said third cladding part; and
 wherein said optical fiber satisfies the following conditions:
   0.19  a/c ≦0.4, and
 
   0.4≦ b/c ≦0.8
 
 
 
       where a is the outer radius of said center core region, b is the outer radius of said first cladding part, and c is the outer radius of said second cladding part. 
     
     
       7. A dispersion compensator according to  claim 1 , wherein said optical component has a mode field diameter of 4.5 μm or less at a wavelength of 1550 nm. 
     
     
       8. A dispersion compensator, comprising:
 an optical component having an accumulated chromatic dispersion of −600 ps/nm or more but less than −300 ps/nm at a wavelength of 1.55 μm; and 
 a housing having a volume of 310 cm 3  or less for accommodating said optical components, 
 wherein said optical component includes an optical fiber coil which is obtained by winding an optical fiber in a coil form such that an insertion loss of said entire dispersion compensator becomes 3.9 dB or less while being accommodated in said housing. 
 
     
     
       9. A dispersion compensator according to  claim 8 , wherein the volume V (cm 3 ) of said housing and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     V ≦−0.31× AD +120.
 
 
     
     
       10. A dispersion compensator according to  claim 8 , wherein the insertion loss IL (dB) at the wavelength of 1.55 μm and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     IL ≦−0.0033× AD +1.9.
 
 
     
     
       11. A dispersion compensator according to  claim 8 , wherein an optical fiber constituting said optical fiber coil comprises;
 a center core part extending along a predetermined axis and having a predetermined maximum refractive index; 
 a first cladding part, provided on an outer periphery of said center core part, having a refractive index lower than that of said center core part; 
 a second cladding part, provided on an outer periphery of said first cladding part, having a refractive index higher than that of said first cladding part; and 
 a third cladding part, provided on an outer periphery of said second cladding part, having a refractive index lower than that of said second cladding part. 
 
     
     
       12. A dispersion compensator according to  claim 11 , further having, as a characteristic at the wavelength of 1.55 μm, a bending loss of 0.1 dB/km or less in a state wound at a diameter of 60 mm. 
     
     
       13. A dispersion compensator according to  claim 11 , wherein said second cladding part has a relative refractive index difference of 0.2% to 0.9% with reference to the refractive index of said third cladding part; and
 wherein said optical fiber satisfies the following conditions:
   0.19≦ a/c <0.4, and
 
   0.4≦ b/c ≦0.8
 
 
 
       where a is the outer radius of said center core region, b is the outer radius of said first cladding part, and c is the outer radius of said second cladding part. 
     
     
       14. A dispersion compensator according to  claim 8 , wherein said optical component has a mode field diameter of 4.5 μm or less at a wavelength of 1550 nm. 
     
     
       15. A dispersion compensator, comprising:
 an optical component having an accumulated chromatic dispersion of −300 ps/nm or more but less than −180 μm at a wavelength of 1.55 μm; and 
 a housing having a volume of 260 cm 3  or less for accommodating said optical components, 
 wherein said optical component includes an optical fiber coil which is obtained by winding an optical fiber in a coil form such that an insertion loss of said entire dispersion compensator becomes 2.9 dB or less while being accommodated in said housing. 
 
     
     
       16. A dispersion compensator according to  claim 15 , wherein the volume V (cm 3 ) of said housing and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     V ≦−0.31× AD +120.
 
 
     
     
       17. A dispersion compensator according to  claim 15 , wherein the insertion loss IL (dB) at the wavelength of 1.55 μm and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     IL ≦−0.0033× AD +1.9.
 
 
     
     
       18. A dispersion compensator according to  claim 15 , wherein an optical fiber constituting said optical fiber coil comprises;
 a center core part extending along a predetermined axis and having a predetermined maximum refractive index; 
 a first cladding part, provided on an outer periphery of said center core part, having a refractive index lower than that of said center core part; 
 a second cladding part, provided on an outer periphery of said first cladding part, having a refractive index higher than that of said first cladding part; and 
 a third cladding part, provided on an outer periphery of said second cladding part, having a refractive index lower than that of said second cladding part. 
 
     
     
       19. A dispersion compensator according to  claim 18 , further having, as a characteristic at the wavelength of 1.55 μm, a bending loss of 0.1 dB/km or less in a state wound at a diameter of 60 mm. 
     
     
       20. A dispersion compensator according to  claim 18 , wherein said second cladding part has a relative refractive index difference of 0.2% to 0.9% with reference to the refractive index of said third cladding part; and
 wherein said optical fiber satisfies the following conditions:
   0.19≦ a/c <0.4, and
 
   0.4≦ b/c ≦0.8
 
 
 
       where a is the outer radius of said center core region, b is the outer radius of said first cladding part, and c is the outer radius of said second cladding part. 
     
     
       21. A dispersion compensator according to  claim 15 , wherein said optical component has a mode field diameter of 4.5 μm or less at a wavelength of 1550 nm. 
     
     
       22. A dispersion compensator, comprising:
 an optical component having an accumulated chromatic dispersion of −180 ps/nm or more but less than −80 ps/nm at a wavelength of 1.55 μm; and 
 a housing having a volume of 200 cm 3  or less for accommodating said optical components, 
 wherein said optical component includes an optical fiber coil which is obtained by winding an optical fiber in a coil form such that an insertion loss of said entire dispersion compensator becomes 2.5 dB or less while being accommodated in said housing. 
 
     
     
       23. A dispersion compensator according to  claim 22 , wherein the volume V (cm 3 ) of said housing and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     V ≦−0.31× AD +120.
 
 
     
     
       24. A dispersion compensator according to  claim 22 , wherein the insertion loss IL (dB) at the wavelength of 1.55 μm and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     IL ≦−0.0033× AD 1.9.
 
 
     
     
       25. A dispersion compensator according to  claim 22 , wherein an optical fiber constituting said optical fiber coil comprises:
 a center core part extending along a predetermined axis and having a predetermined maximum refractive index; 
 a first cladding part, provided on an outer periphery of said center core part, having a refractive index lower than that of said center core part; 
 a second cladding part, provided on an outer periphery of said first cladding part, having a refractive index higher than that of said first cladding part; and 
 a third cladding part, provided on an outer periphery of said second cladding part, having a refractive index lower than that of said second cladding part. 
 
     
     
       26. A dispersion compensator according to  claim 25 , further having, as a characteristic at the wavelength of 1.55 μm, a bending loss of 0.1 dB/km or less in a state wound at a diameter of 60 mm. 
     
     
       27. A dispersion compensator according to  claim 25 , wherein said second cladding part has a relative refractive index difference of 0.2% to 0.9% with reference to the refractive index of said third cladding part; and
 wherein said optical fiber satisfies the following conditions:
   0.19≦ a/c <0.4, and
 
   0.4≦ b/c ≦0.8
 
 
 
       where a is the outer radius of said center core region, b is the outer radius of said first cladding part, and c is the outer radius of said second cladding part. 
     
     
       28. A dispersion compensator according to  claim 22 , wherein said optical component has a mode field diameter of 4.5 μm or less at a wavelength of 1550 nm. 
     
     
       29. A dispersion compensator, comprising:
 an optical component having a predetermined accumulated chromatic dispersion at a wavelength of 1.55 μm; and 
 a housing for accommodating said optical component, 
 wherein said optical component includes an optical fiber coil which is obtained by winding an optical fiber in a coil form such that the volume V (cm 3 ) of said housing and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     V ≦−0.31× AD +120
 
 
 and such that the insertion loss IL (dB) at the wavelength of 1.55 μm and the accumulated chromatic dispersion AD (ps/nm) of said optical component satisfy the following relationship:
     IL ≦−0.0033× AD +1.9.
 
 
 
     
     
       30. A dispersion compensator according to  claim 29 , wherein an optical fiber constituting said optical fiber coil comprises:
 a center core part extending along a predetermined axis and having a predetermined maximum refractive index; 
 a first cladding part, provided on an outer periphery of said center core part, having a refractive index lower than that of said center core part; 
 a second cladding part, provided on an outer periphery of said first cladding part, having a refractive index higher than that of said first cladding part; and 
 a third cladding part, provided on an outer periphery of said second cladding part, having a refractive index lower than that of said second cladding part. 
 
     
     
       31. A dispersion compensator according to  claim 30 , further having, as a characteristic at the wavelength of 1.55 μm, a bending loss of 0.1 dB/km or less in a state wound at a diameter of 60 mm. 
     
     
       32. A dispersion compensator according to  claim 29 , wherein said second cladding part has a relative refractive index difference of 0.2% to 0.9% with reference to the refractive index of said third cladding part; and
 wherein said optical fiber satisfies the following conditions:
   0.19≦ a/c <0.4, and
 
   0.4≦ b/c ≦0.8
 
 
 
       where a is the outer radius of said center core region, b is the outer radius of said first cladding part, and c is the outer radius of said second cladding part. 
     
     
       33. A dispersion compensator according to  claim 29 , wherein said. optical component has a mode field diameter of 4.5 μm or less at a wavelength of 1550 nm.